from typing import List, Dict, Optional
from datetime import datetime
from fastapi import HTTPException
from models.meal import Meal
from schemas.meal import MealCreate, MealUpdate

def validate_meal_name(name: str) -> bool:
    """
    Validate the meal name.

    Args:
        name (str): The meal name to validate.

    Returns:
        bool: True if the meal name is valid, False otherwise.
    """
    return bool(name.strip())

def get_available_meals(db_session) -> List[Meal]:
    """
    Get the list of available meals from the database.

    Args:
        db_session: The database session.

    Returns:
        List[Meal]: A list of available meals.
    """
    return db_session.query(Meal).filter(Meal.is_available == True).all()

def get_meal_by_id(db_session, meal_id: int) -> Optional[Meal]:
    """
    Get a meal by its ID from the database.

    Args:
        db_session: The database session.
        meal_id (int): The ID of the meal to retrieve.

    Returns:
        Optional[Meal]: The meal object if found, None otherwise.
    """
    return db_session.query(Meal).filter(Meal.id == meal_id).first()

def create_meal(db_session, meal_data: MealCreate) -> Meal:
    """
    Create a new meal in the database.

    Args:
        db_session: The database session.
        meal_data (MealCreate): The data for creating a new meal.

    Returns:
        Meal: The created meal object.

    Raises:
        HTTPException: If the meal name is invalid.
    """
    if not validate_meal_name(meal_data.name):
        raise HTTPException(status_code=400, detail="Invalid meal name")

    new_meal = Meal(
        name=meal_data.name,
        description=meal_data.description,
        price=meal_data.price,
        is_available=meal_data.is_available,
        created_at=datetime.utcnow(),
        updated_at=datetime.utcnow(),
    )

    db_session.add(new_meal)
    db_session.commit()
    db_session.refresh(new_meal)

    return new_meal

def update_meal(db_session, meal_id: int, meal_data: MealUpdate) -> Optional[Meal]:
    """
    Update an existing meal in the database.

    Args:
        db_session: The database session.
        meal_id (int): The ID of the meal to update.
        meal_data (MealUpdate): The updated data for the meal.

    Returns:
        Optional[Meal]: The updated meal object if found, None otherwise.

    Raises:
        HTTPException: If the meal name is invalid.
    """
    meal = get_meal_by_id(db_session, meal_id)
    if not meal:
        return None

    if not validate_meal_name(meal_data.name):
        raise HTTPException(status_code=400, detail="Invalid meal name")

    meal.name = meal_data.name or meal.name
    meal.description = meal_data.description or meal.description
    meal.price = meal_data.price or meal.price
    meal.is_available = meal_data.is_available or meal.is_available
    meal.updated_at = datetime.utcnow()

    db_session.commit()
    db_session.refresh(meal)

    return meal